An apparatus includes a circuit having a heat-generating circuit component, and
structure for guiding a two-phase coolant along a path which brings the coolant
into direct physical contact with either the circuit component or a highly thermally
conductive part which is thermally coupled to the circuit component. The coolant
absorbs heat generated by the circuit component, at least part of the coolant changing
from a first phase to a second phase in response to the heat absorbed from the
circuit component, where the second phase is different from the first phase.