How can one demonstrate the existence of atmospheric pressure using a crushing can experiment?

OK..here's a low budget expt u can try @ home gettan empty coke/lager/beer can..add abt 30ml water..put it on stove till water is boiling..now quikly grab can (oven gloves!) and invert over water in sink/basin..the water surface forms a seal..the steam condenses inside the can forming partial vacuum..and external atmos P crushes the can!