1) Boil 2) Boil excessively 3) Boil over 4) To boil excessively 
• (v. i.) To boil over or unduly.
O`ver·boil' intransitive verb To boil over or unduly. « Nor is discontent to keep the mind Deep in its fountain, lest it overboil In the hot throng.» Byron. 
[v] - boil excessively