As far as the Liquid Plumbr/Drano with foil creating an explosion, I did experiment with this as a kid...
We tried to make a "Hindenburg" by taking a glass soda bottle and mixing the two components and placing a regular party balloon on the lip of the bottle...thus filling it up with gas. Then you could, theoretically, rig up a fuse, pinch off the balloon and light it while sending it up in the air. The "Hindenburg"
My buddy had read about it somewhere. Again, this is going back about 25 years, but we could never get it to work. The vapor of the drain cleaner would always deteriorate the balloon, and/or there was still residue from the drain cleaner on the lip of the bottle causing the balloon to give out. We were kids, we weren't very careful about it.
That's why I said that I believe the chemical reaction creates Hydrogen Gas.
At any rate, we were kids just screwing around. We never sealed off a bottle to see if it would explode...