Eli5 what would happen if you had water in a completely sealed container and brought it past boiling temp

Question

Would it just turn into a pressurized container full of steam? Would the water stay water but just like, really hot?

In: 98

Answer 1

Think of the radiator and cooling system in most cars – you can use plain old water in your car’s cooling system, and the pressure allows it to be higher than boiling and can carry more heat to the radiator. (Antifreeze is used because it has a higher boiling point and lower freezing point than plain water, so it’s more effective for cooling and safer in the winter since frozen water expands and can break things, and there’s anti-corrosion agents and I assume it’s a better lubricant for the water pump?)

Not a scientist but that’s how I understand what’s going on, and why if you open the cap on a hot radiator, you get a pretty dangerous, explosive release of steam and boiling coolant due to the sudden release of pressure allowing the liquid to suddenly expand.