Not certainof this cause, mind you, but sometimes potatoes (more often larger ones) have air spaces in the center. If small in proportion to the surrounding substance, it makes sense that extreme heat would crate steam and pressure within. One poke and just like a balloon!

Potatoes are 79% water. Most foods except drygoods are better than 50% water if it has an enclosing membrane of any sort you build up pressure as the water turns to steam and it explodes. Should see a whole egg in a microwave.

OMG! Canned potato's? Is there such a thing?

Spike it first.

Alright I get it, I should have pricked them first but they looked like they had lost any innocence and therefore their virginity. I really don`t think it was the potatoes themselves that exploded but some trapped water underneath.

Real potatoes should be stabbed with a fork to let steamout before you put in oven. I've used potatoes out of a can but sliced and baked in casserole with onions and cheese. Glad you're okay.

Ugh! But just think how clean the oven will be after you scour every last nook & cranny of it! Lol!
I had Just bought my new to me RV, lifted up a jar of very soupy salsa,the lid failed, the full jar bounced off the counter & onto the floor...after 6 years, I still occasionally find a bit of dried salsa.

Baked potato exploded in the oven because I forgot to lance it. Quite messy.

You are supposed to pierce potatoes several times with a knife before putting them into an oven or microwave.