I think with tins, it was rumoured that if you boiled them without making a hole in the tin, they'd blow up and take out a city block.
I'm a Scout leader. One of our Patrols once chucked a can of peaches on their fire, because they didn't want it. I checked with the PL that he had opened it first, and he said, "Of course".
A few minutes later there was a massive bang. Their entire fire was blown out of the altar, and bits of burning wood descended around the site. We were finding small, blackened holes in tents for days afterwards.
Clearly his definition of open was different from mine. It transpires that various Scout leaders have stories like this.
Burning tins to get rid of small remnants of food is good practice, but it's usual to take off the lid and empty them first...