Way to cook hot dogs in a microwave without them bursting

In short, kind of, but only with the proper accessories/equipment. You'll never match a grill or griddle but you can get surprisingly close.

As was mentioned in other answers, what you're going to lose most is the sear.

I was given a Corningware Microwave Browning Dish a while back and found that it actually works pretty well when you're stuck with only a microwave. They were apparently popular when microwaves were new and exciting, but people didn't know how to use them well and they faded into oblivion. I've seen them on sale on eBay so you might be able to find a good price there if you're going to be stuck in the hostel for a while.

The basic idea is, there's a special kind of microwave-safe metal inside the base of the casserole. You heat this with nothing on it for 3 minutes to get it nice and hot. When you drop the patty on, it immediately sizzles. You use the microwave function to heat the inside, while the hot surface sears the outside. Although you're likely not going to get a perfect burger, you do get a real nice Maillard reaction on the outside of both sides (assuming you flip halfway) and if you play with the cooking time and power (to reduce that rubbery texture from overcooking), you can get something that's (in my opinion) a good 75%-quality burger compared to a griddle or grill. I actually burned pork chops on it once, that's how hot the surface gets.

As a bonus, similar to a nice Boos block, there is a gutter around the outside and the plate is slightly concave, so the juices run off into the reservoir and the burger won't sit in fat during the cooking.

After reading the other answers (ElendilTheTall's specifically), I would think if you combined the steaming method to cook the burgers, with the microwave browning dish to sear, you could probably get a really good result. If the burgers were fully cooked via steaming you could probably heat the dish and sear the burgers without even turning the microwave on (except to heat the casserole initially).

I believe Alton Brown did an episode where he talked about a specific type of brick that you can find at most hardware stores which is microwave-safe for the same searing purpose, but I can't find that info right now.

It sounds like you pretty clearly had too much water, and maybe cooked too long and too hot. As for what to actually do: using a microwave doesn't mean you can't be flexible. You can figure out how to cook them the same way you could figure out how to cook many things in the microwave.

Start just enough water to cover the lentils. Cook it on high until it's nearly boiling; then reduce the power until it can keep going without boiling much. (That depends completely on your microwave; on mine it'd probably be in the 20-50% range.) Every couple minutes, have a peek. Make sure there's still enough water; stir them and see if they're done.

If you keep track of the total time, and the amount of water you had to add as you went along, you should be able to do it without much trouble next time. (And if you like, leave out the initial heating on high; that just saves some time.)

Mushiness can be caused by cooking too long, obviously, but also by cooking too hot. A rapid boil can help disintegrate things. It's especially tricky to avoid boiling in a microwave, since reducing power just makes it go off and on. Pay attention to how much it's boiling while it's on; while it's off it'll still be plenty hot.