A method for producing concentrated HCl vapor from an aqueous solution of HCl, including: (a) introducing an aqueous feed liquor to an evaporation chamber containing a mother liquor, the feed liquor having an initial, super-azeotropic HCl concentration; (b) directly contacting a liquor of these liquors with a heat-laden heat transfer fluid, to transfer heat from the fluid; (c) utilizing the heat to evaporate HCl, within the chamber, to produce the concentrated HCl vapor and to produce the mother liquor, the mother liquor including an aqueous phase having a reduced concentration of HCl, with respect to the initial HCl concentration; (d) subjecting the mother liquor to a liquid-liquid separation to produce a liquid phase containing HCl, and another liquid phase containing the heat transfer fluid in a heat-depleted state, with respect to the heat transfer fluid in step (b); (e) heating the heat transfer fluid in the heat-depleted state, to regenerate the heat-laden heat transfer fluid, and (f) returning this heat transfer fluid to step (b).