It doesn't freeze - one use of anti-freeze is in your cars radiator it stops it from freezing up in the winter, no anti freeze and you run the risk of a frozen radiator, car over heating or even worse a cracked engine block.
No... they have a similar function in absorbing heat and exchanging it to the ambient air, but that's where the similarity ends.
your radiator cap is probably bad, and its pushing too much out at once, try replacing the cap