Abstract: The invention relates to a vapor-compression method. The aim of the invention is to provide such a method respectively a system with which a distillation with a further reduced energy requirement is possible, which simultaneously operates reliably, with little maintenance, and with only little available power, in particular when starting, and which is able to handle fluctuations in the available power. This is achieved in that an aqueous solution is preheated and fed to an evaporator at a lower end in order to generate vapor. The vapor is conducted from an upper end of the evaporator to a compressor (V) in order to be compressed. The vapor that is compressed in the compressor (V) is used to supply energy to the evaporator. The vapor that is thus cooled or optionally at least partly condensed is used to preheat the aqueous solution.