Device (10), comprising a platform (14) for placing a vessel (9) containing the liquid, a pipe (15) with an open end (151) configured for supplying steam to the vessel, a driving device (17) configured to actuate a relative movement between the end of the pipe and the platform, means (140) for determining a liquid level of the liquid in the vessel, and a control unit (18). The control unit is configured to actuate the driving device (17) so that a relative initial position between the end of the pipe and the platform is assumed on the basis of the liquid level. The means (140) for determining the liquid level comprise a weighing device. The control unit is then configured to determine the liquid level from the weight.
