There is no chemical solution that I can think of as those require your system to still be full of liquid. Thermite works, but would like cause other problems. Napalm is also quite effective, but a little too effective.
Thawing or melting anything with heat relies on a few factors, including (but not limited to) the thermal coefficient of the material, “Delta-T” or temperature differential, simple geometry (or the thickness of the material). You really don’t need all that much heat if you are patient. Any temperature above freezing will work if you give it enough time.
I have used a hair dryer and a bit of patience to solve cold-related car issues before, but it took all night.
@Tropical_Willie I also use the Rain-X stuff sometimes, but I find that it clouds up the windshield pretty badly for a few moments in the wintertime, especially if your defroster hasn’t warmed up yet. I am not a fan of driving completely blind for even a few seconds seconds at 60MPH.