Battery Boiling over problems

Test the voltage of the battery . With the car off it should be 12.5 to 12.8 if its higher the battery is overcharged . With the motor running the voltage should be slightly hire 13.7to 14.7 volts if its running higher were looking at an over charge condition . This is caused by a faulty voltage regulator . Not all cars have a voltage regulator in the alt some are external to the alt. Finally the issue could be a bad battery check the posts and see if either is loose . If you can move the post replace the battery. If the battery smells of acid you should replace the battery. If the sides or bottom are swollen or leaking replace the battery . if the battery is fine then you can clean the corrosion with water and baking soda . once clean cover the post and terminal with grease to prevent further corrosion . Hope this helps