Making a 'gusher' with compressed air

Secure a large narrow-necked bottle like as is used for soda water. Place a single-hole stopper in the bottle. By the stopper put a 10- cm length of glass tube which has been drawn to a jet on the outside end. With a short length of rubber tube join a length of glass tube that will extend nearly to the bottom of the bottle. Fill the bottle about half full of water. Insert the stopper firmly and hold it in with your fingers. Next blow hard into the bottle; and when you free the pressure, point the bottle away from you. What happens?