my cars over heating? ( rover 200 1.4 )?

my car keeps over heating i,ve put a new thermostat in and theres still no change. i,ve checked that radiator has no blocks in it then wen i filled it up with water just above the min level i ran it for ten minutes and all the pipes had swelled up and were red hot and the water levl was rite up passed the max level !! any ideas please ???