Chemical reactions are known to accelerate when reactants are present in microdroplets. In this case, the reaction rate increases by orders of magnitude with decreasing droplet size. This phenomenon has long attracted the attention of researchers, but remains understudied, despite its great practical importance. Laboratory studies require the use of steadily levitating small droplets of water of a given constant size and temperature with dissolved substances in the droplets. Clusters of droplets that form over a locally heated water surface meet these conditions. This work is a preliminary stage of laboratory studies of biochemical processes in individual droplets. The effect of salt (NaCl) dissolved in water on the behavior of droplet clusters, including the formation of equilibrium clusters from saline water droplets during their infrared irradiation, was investigated. Experimental results are presented which show for the first time that even a small salt concentration significantly affects the condensational growth of droplets and their equilibrium size, which is achieved only when the salt concentration is below a certain threshold value. The dependence of this concentration threshold on the surface temperature of the pure water layer under the levitating cluster has been determined. The proposed approximate model that takes into account the kinetics of water evaporation and salt diffusion appears to be insufficient to agree well with experimental data. The authors believe that a physical reason for the additional decrease in the intensity of evaporation from the upper surface of the droplet is the partial crystallization of salt near the irradiated droplet surface.