So the Frontier developed a leak, and it got bad enough that it was only holding a charge for a month or two, so I decided to fix it. I got a loaner vacuum pump from AutoZone, some o-rings to replace the ones at the compressor that my leak sniffer said were leaking, and went to town. In my shadetree research online, I noticed someone suggest leaving your cans of 134a in the sun to help the gas expand and feed into the system more quickly. Not to be outdone, I decided that if sitting them in the sun was a good idea, heating up some water on the stove and letting the refrigerant take a hot bath before charging would be even better.
So yeah... near boiling water, and cans of 134a aren't the best combination. Luckily, I took the pot of water outside before I put the can in. I was also fortunate that my 8 year old son actually listened to me and didn't stand right next to the can. It exploded while I walked inside to get an oven mitt, and I didn't find the top of the can until several hours later when I noticed it about 50 feet away in the road.
So learn from my dumbassery... not only, don't heat up your can of refrigerant - but be safe in general. Wear safety glasses. Wear gloves. Pay attention to what you're doing. I discovered from this article that refrigerant is packed in cans that are only designed to hold up to 180 PSI.
https://www.chemaxx.com/aerosol13d.htm This poor bastard lost an eye when he sat a can of refrigerant on his intake manifold.
My refrigerant at probably somewhere around 180 degrees was pushing 400 PSI! But even a normally charged system is over 200 PSI on the high side. So mess up and open the wrong valve on your manifold to "charge" the high side and you could have a bloody mess!