Abstract <p>Increasing the mass transfer rate in electrodialysis allows for a reduction in the area of expensive membranes and, in some cases, lowers the cost of the final product. It has been experimentally established that an increase in the concentration of a KCl solution (from 0.02 to 0.75 M) in the concentrate chamber of a flow-through electrodialysis cell (<i>c</i>_c) leads to a significant growth in the limiting current density (<i>i</i>_lim) through the MA-41P anion-exchange membrane, provided that the desalination chamber contains a solution with a constant concentration (0.02 M KCl). This growth (36% at <i>c</i>_c = 0.5 M) significantly exceeds the value (4%) that could be expected due to the increase in diffusion and electromigration transport of co-ions through the membrane caused by the increase in <i>c</i>_c. As the experiment shows, an increase in <i>c</i>_c leads, on the contrary, to a decrease in the rate of H⁺ and OH^– ion generation at the solution/membrane boundaries, which could also contribute to an increase in the limiting and overlimiting current density. Using voltammetry, chronopotentiometry, and pH-metry, it is shown that the observed growth in <i>i</i>_lim may be associated with the emergence of unstable equilibrium electroconvection, the possibility of which was theoretically predicted in the works of Rubinstein and Zaltzman.</p>