How do you get water to 400 oC?Easy, you superheat it…
Superheated water is found naturally on the earth in underground water supplies – we see it coming to the surface as a geyser. It is also found in man made phenomena such as power stations.
But how is it superheated?
The key ingredient is Pressure. The pressure stops the water boiling and keeps it liquid – if the pressure is reduced (such as the geyser rushing out of the earths crust) it will boil and cool down.