A microwave energy emitter (108) is positioned in a microwave transparent chamber (123) within a material holding vessel (106) of a microwave containment vessel (122). The holding vessel (106) may be transparent to microwave energy and is further provided with a microwave reflective component outward, on, or beyond an exterior surface (121) of the wall of the holding vessel (106). The microwave reflective component reflects microwaves back into the fluid holding vessel (106). The fluid holding vessel (106) encloses a material that absorbs microwave energy. An inlet path (116) and outlet path (112) is provided for the material to flow in and out of the vessel upon predetermined conditions. Heated material can be condensed via a condenser (124) into a collection vessel (120). A controller (126) is provided to send control signals to a switching device (100) for controlling the material flow and receiving sensing signals for decision generation.