Cut Potatoes into 1" thick rounds, then cut in 1/2.
In a separate pot, combine sugar, butter, water, and salt. Simmer until dissolved and reduced slightly, 10-15 minutes on low.
Place sweet potatoes in a single layer in large glass baking dish. Pour sugar mixture over sweet potatoes and bake, basting and turning occasionally, until potatoes are soft and have a caramelized coating.