Now your getting into paranormal area. I find that one very hard to swallow.
Years ago I bought some WW2 surplus 45acp, a friend and i took it to the range. I chambered a round, dropped the hammer, no pop, nothing...Held it there a few seconds downrange, then reached for the slide to eject the round. Then it went off and left a 45 caliber hole in the metal covering over our heads.
Years later was shooting 45acp again, a friend had some loose rounds on the table. He said, try some of these. I walked over and held out my hands as he raked some into my hands. One round missed my hands and fell to the ground, exploding as it did. We both jumped back, and we both got some small metal fragments in our legs.
Upon close inspection there was ONE nickel sized piece of rock protruding from the worn dirt path/shooting post. The 45 round had decided to land upright on that small rock and detonate. We never found the bullet, but my leg bled for a while from shrapnel. I was wearing shorts (summertime in Texas).
Last year I was at a rifle range and a guy was trying to sight in an ak-47 variant. A cease fire was called and the guy placed his rifle in the rack. I was boxing up some gear when a huge boom came from his lane. I thought he'd had an AD, but his gun was in the rack. He had dropped a round, on concrete, and it had went off, scaring the BeJesus out of us all.
Go to a reloading forum, there's 1000's of stories much more incredible than these. All this stuff Can and Will happen, just a matter of time.