Answer
This is a hands-on demonstration. The steam in the can condenses when it touches the surface of the cold water, reducing the vapor pressure inside the can and allowing atmospheric pressure to crush the can.
If you use hot (but not boiling) water in the pan, it will still condense the steam in the inverted can, lowering the pressure inside and causing it to collapse, but the crushing will not be as spectacular.
If you use boiling water in the pan, no net condensation will occur inside the can, and it will not be crushed.