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

Two things would happen. First, just like you said, it would continue to be water but really hot since the boiling point of water rises with pressure. You get this interesting cycle of water boiling, turning to steam, increasing the pressure, the increased pressure stops the boiling until it gets hot enough to boil again at that pressure. This cycle repeats until the pressure overcomes the ability of the vessel to hold said pressure. Then you get a steam explosion where the vessel explodes and rapidly reduces the pressure but not the temperature causing the water to turn to steam very quickly and violently. For reference, water boils at 100c at 14.7psi (atmospheric pressure) but at 225psi water don’t boil until 200c.