Hah! I remember doing something similar. I remember as a fng, pinching off a piece of c4 and putting in under a can of spaghetti to cook. I didn't pay a lot of attention to it and found out that you have to poke a hole down through it to vent. Did you ever try to get a plug of spaghetti back in the can? 
I got lucky, used the heat tabs when I was with C1/9 (yes the walking dead!) or ate them cold out of the can for a year, state side I was in a multi channel radio platoon and we had micro wave radio vans, heat a can of rats was easy, com wire it to a 10 foot stick, crack the can open to vent, hold it in front of the outgoing antenna, key the mic on hi tropo for 15 seconds, voila! anymore than 20seconds and you have charcoal!