An evaporator is provided for evaporation of liquid from a solution or liquid mixtures, together with methods of operation of the evaporator. The evaporator comprises a chamber (1); a liquid reservoir (3) for holding a heat transfer liquid exposed to the interior of the chamber; a support (6) for supporting a container (8) in the chamber, such that the liquid sample in the container is exposed to a fluid path (15) for connection to a condenser (16), the fluid path being separated from the chamber interior, and at least a portion of the container is closely thermally coupled to the chamber interior; and means (4) for heating the heat transfer liquid in the reservoir to create heat transfer liquid vapour, which in use condenses and releases latent heat of vaporisation to the liquid sample in the container. As the temperature of the sample is dependent on the saturated vapour temperature of the liquid in the reservoir, the temperature of the samples is reliably limited, thereby avoiding overheating. High levels of heat energy may be delivered controllably to the samples, enabling a high evaporation rate to be achieved at relatively low temperature.