Remarkably different behaviors are found when comparing micro- scale flow boiling heat transfer data by distinct authors, even under similar experimental conditions. Such differences are almost certainly related to the complexity of confined forced-flow boiling. Certain aspects of the phenomenon, which are negligible in the macro- scale, become surprisingly relevant when the system size becomes small. From the results reported in the literature on the thermal- fluid features of evaporating flows in small channels, the following study presents a discussion concerning convective boiling heat transfer, highlighting the aspects that are characteristic to confined two- phase flows.