Right, i was with my cousin in the car the other day driving home from town.. Traffic as usual, and i saw the temp gauge going to 100 but i thought the radiator might come in but no. it reached almost 110 degrees and then fumes from the boiling coolant came out of the bonnet and i stopped urgently in an estate. released the bonnet and and i saw the coolant boiling in the water tank. never had this problem before. Any suggestions ?
thermostat, water pump ?
later edit; The car is '96 astra f