This happened in my old apartment. I came home one night and stepped into the kitchen (in the dark) and heard an almighty cracking sound. Thinking I was about to fall through the floor I jumped about ten feet and slowly inched around 'till I found the light. There was a mini volcano of tiles that I had just half stepped on…truly one of the weirdest things I’ve seen in my life :shock:
I didn’t know what the hell it was, for a week me and my roommates gingerly stepped around it anytime we went to the kitchen!!
It seems that the bonding underneath the tiles often slips (maybe flooding related or from the contraction or expansion of old concrete). I believe it’s related to the cold snap we have and the cold caused the walls or the concrete to contract but the tiles have a different ‘heat’ index or whatever because it happened during the first real cold snap of last year.
. Anyway the best thing to do is take the carpet up and take a hammer to the hump if it consists of tiles(tell your landlord to get over and fix it too).
If its not made of tiles I’d be worried. My landlord told me this was common in the old apartments.