MGF Steam at Back

HI

This evening gave my 2001 MGF a run after a short distance . noticed steam coming out of the back , pulled up straight away ,

Oil pressure and temparture dials were okay but all the water coolant had gone out of the tank , it was full this afternoon as it was checked ,



Noticed on the road a line of water going back a few hundred yards , what water was left in the tank was boiling



Let everything cool down as much as i could , i carry water so topped it all up and it ran home okay



Any ideas what may have caused it or what i need to check

thanks to those who reply

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