yeah, at least in colder climates, it freezes way faster than you'd expect. Basically instantly, with a bad habit of pooling around the wipers

edit: turns out some people have also tried boiling hot water... I'd never have thought to try this, but, yeah, it'll crack your windshield.

some people will recommend rubbing alcohol blends, which work a little better, but they can dry out the rubber seals around the window. It's honestly better to just start the car 5 mins earlier than you need to use it, with the defrost on full blast, then come out and scrape it.