How is it possible to supercool water, so that it remains liquid even below freezing point?
you can disolve things like salt into it.
No, that isn't supercooling, that's actually lowering the freezing point.
Supercooling is when you cool the water below freezing, but it is so pure and so undisturbed that there is nowhere for crystals to start forming. So having a clean container and doing it slow is pretty important.
Separate names with a comma.