I had a 200-lb, square, solid dresser tip over and CRASH to the floor at 3 AM, while I was right next to it.
I was lying in bed with the laptop less than two feet away, and saw something move out of the corner of my eye. I looked up, and past the glare of the LCD I could see the shadowed corner of this huge-ass dresser tipping up, and it was so impossible that I just sat there staring blankly at it, thinking (if I thought at all) 'I'm not really seeing that. That isn't real'.
Time seemed to slow to a crawl as this huge heavy dresser, silhouetted in the hallway light, teetered up on its two front legs, leaned past the center of gravity, swayed out and then landed with the most terrific crash. It shook the whole apartment. (I bet the neighbors were pleased.)
It scared me into a state of catatonia. I just sat there as my boyfriend raced into the room, asking me what had happened, and I couldn't move or speak. I just looked at him, then turned over in bed and sort of went to sleep from fear, something I haven't done since childhood.
There was no explanation for that. Two people had to work together to move it anywhere, and I was sitting right the fuck there and watched it tip out and over. It was against an outside wall in a second-floor apartment. That thing moved by itself. Nothing else could possibly have moved it short of an earthquake, and there wasn't one.
In that same apartment, we had a container of coffee fall off the microwave with no one in the room, just tipped out and there was coffee in a fan across the floor. That one's harder to call 'unexplained' because no one was there and I guess it could have been natural. But that dresser? No way. That was strange.