We bought a house a year ago, and for all that time the toilet has sat sturdily on the floor, not rocking or making any noise when you get up. But just yesterday, it has started to make a loud "pop" from what seems to be the floor whenever you get up. It's a very loud, noticeable noise, and it happens whenever you remove weight from it (but DOESN'T make the sound when you put weight on). The toilet doesn't rock or shift whatsoever, even pushing it very hard it doesn't budge. Any suggestions what could cause this to suddenly start happening? I'm worried that the wax ring could be deteriorating, or worse, that there could be subfloor damage.