When we turn up the kitchen sink water (hot or cold), around 75-80% full, the water starts getting choppy and the faucet head starts bouncing up and down. At lower flow levels, there's no issue. The hot water seems to take a little longer to hit that state than the cold water.
We have one of those PUR water filters attached, and I noticed that there was no issue with the filter switched on (although that might be just due to low overall throughput) so I tried taking the filter off. No choppiness or bouncing, but it sounds funny, almost like too much air is getting in, and a few seconds after I shut it off, I get a second gush of water. This might be due to a lack of aerator (said aerator being built into the filter), I guess, but I'm adding what data I can.
This happened after our backyard neighbor (a bit downhill) started getting water coming out of their yard yesterday, although our problem only started around 4 PM today. There are no other reported issues were can find online for our area.
Best Answer
I'm still not certain why exactly this happened, but removing the filter fixed the thumping/choppy problem, and replacing the aerator fixed the second gust of water problem.
My suspicion at this point is that the filter either just spontaneously failed, or something in the water conditions around the time my neighbor had his problem caused a buildup of debris or something like that. We hadn't replaced the filter cartridge in it for some time anyhow (my wife found that it didn't seem to affect the water's taste much), so it was not a huge loss to us, just a baffling mystery at the time.