We had a few cans of hot cocoa and cappuccino once that had a thing on the bottom that you "popped" and it heated up and while they were fun to have in the car for winter emergencies and tasted ok they were so darned expensive they weren't worth it.
It also seemed that around the same time they came out Dinty Moore had a "heat it self and eat" type product and they were ok too. But uber expensive.
ETA: I just searched it and found that the brand was Hillside hot coffees and cocoas but the company has gone out of business. Haven't found anything on the Dinty Moore and I'm sure that it was them that had their stews and ready to eat pasta meals with self heating packages. Also at walmart of course so who knows.