Embodiments described generally relate to systems comprising a humidifier (e.g., a bubble column humidifier) and a heating device (e.g. a heat exchanger), and associated methods. In certain embodiments, the heating device heats a first liquid stream comprising a condensable fluid in liquid phase (e.g., water) and a dissolved salt (e.g., NaCl) to a relatively low temperature (e.g., about 90° C. or less) prior to the first liquid stream entering the humidifier through a main humidifier liquid inlet. In some cases, the system comprising the humidifier and the heating device requires only low-grade heat to operate, which may be advantageous due to the low cost and high availability of such heat.