Sugar and salt have two VASTLY different solubilities in water. At 20 degrees Celcius, 203.9 grams of sugar will dissolve in 100 grams of water, while only 35.9 grams of NaCl will dissolve in 100 grams of water. So if you were to slowly evaporate the solution, the NaCl will ppt out MUCH sooner than the sugar will as the amount of water dissipates. With both of these solutes, their solubility increases as you heat up the water, so you could also heat the solution along to increase the solubility and remove the water quicker. As it cools, the NaCl will ppt out. Then you can just filter the solution and the filtrate will contain the sugar. Just repeat this process a large number of times, and you'll eventually separate the two solutes.