boiling \boil"ing\, a.
   heated to the point of bubbling; heaving with bubbles; in
   tumultuous agitation, as boiling liquid; surging; seething;
   swelling with heat, ardor, or passion.
   1913 webster

   boiling point, the temperature at which a fluid is
      converted into vapor, with the phenomena of ebullition.
      this is different for different liquids, and for the same
      liquid under different pressures. for water, at the level
      of the sea, barometer 30 in., it is 212 deg fahrenheit;
      for alcohol, 172.96deg; for ether, 94.8deg; for
      mercury, about 675deg. the boiling point of water is
      lowered one degree fahrenheit for about 550 feet of ascent
      above the level of the sea.

   boiling spring, a spring which gives out very hot water, or
      water and steam, often ejecting it with much force; a
      geyser.

   to be at the boiling point, to be very angry.

   to keep the pot boiling, to keep going on actively, as in
      certain games. colloq.
      1913 webster
see also:
boiling point boiling spring to be at the boiling point to keep the pot boiling