Re: popcorn ceiling is peeling
You're discovering why popcorn texture (acoustic texture ) doesn't belong in a bathroom, odds are, it is the moisture level that is the culprit.
The main worry with acoustic texture is the presence of asbestos (pre-1978 structures ), however, I suspect that this was done by an unhandy homeowner more recently, and it was likely to cover up a botched repair job. I have never seen acoustic texture in a bathroom - ever, which is why I suspect a DIY job.
If you are concerned with the possibility of asbestos, then scr-ape a small sample into a ziploc bag and have it tested, your county extension office can help with this. Regardless, you will want to wear a dust mask, as the texture does have silica in it, which isn't much good to breathe either.
You are correct, wetting the texture will make it release much more easily, with much less effort. Use a household spray bottle and thoroughly wet it down. Repeat this several times until the texture releases easily and with minimal dust. Use a drywall knife or similar tool to scr-ape the texture off.
To minimize the mess and clean up, at least lay painter's plastic down on the floor, I would include running plastic on the walls around the room, as this will protect the walls, counters, etc. When you're done, drop everything into the plastic on the floor and then carefully roll it up. Use care not to tear the plastic, or you're going to have a big mess on your hands.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!