How about the common ion effect? Dissolve the sugar-salt mixture in
water. Add copious amounts of potassium chloride. Stir for a long time.
Most of the sodium chloride will precipitate out. Decant and evaporate.
You'll have one vessel with salt and potassium chloride and another
vessel with sugar and potassium chloride. Neither will be pure, but the
problem was to separate (no mention of purity).