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.