If you make instant iced tea, or any kind of powdered drink mix, heres a solution to always having undissolved sugar at the bottom of the pitcher. First measure in however many scoops of mix you need into your pitcher (we use a cleaned out gallon milk jug with a screw top. Using a funnel helps). Then put in a couple inches of HOT tap water and swish it around till all the sugar is dissolved. Then you can add a tray of ice if you have a big enough opening, and fill the rest with cold water. No more weak tasting drinks or sugar at the bottom of the pitcher!
I boil equal quantities of water and sugar together for several minutes, until a light to medium syrup is formed, and then store it in the refrigerator, ready for use in cold drinks.