In supercooled aqueous solutions, ice nucleation is the initial stage of the freezing process. In this paper, we present experimental results that indicate that during the freezing of aqueous solutions, freeze-induced phase separation (FIPS) into pure ice and a freeze-concentrated solution (FCS) takes place. Our observations involve the use an optical cryo-microscope (OC-M), to record images and motes. The results visually indicate for the first time that there are two freezing processes for (NH4)(3)H(SO4)(2)/H2O solutions: contact freezing, as is the case for pure water drops, and (ii) the Wegener-Bergeron-Findeisen process, which is the growth of frozen drops (ice) at the expense of liquid ones. We also present OC-M images of frozen micrometer-scated H2SO4/H2O drops that support our previous finding that freezing of these solutions generates mixed, phase particles, namely an ice core coated with a FCS. These results are relevant for atmospheric as well as for pharmaceutical sciences.