Combine 1/3 of the sugar and water in a large skillet over medium-high heat; bring to a boil. Add orange slices. Sprinkle some sugar over the exposed side; cook until sugar dissolves into the orange slices, 2 to 3 minutes. Flip and repeat on the second side. Drain water.
Flip orange slices and cover with some more sugar; drizzle some maple syrup on top. Cook until sugar dissolves, 1 to 2 minutes. Flip and repeat on the second side. Repeat until orange slices appear candied, scraping any melted sugar off the bottom of the skillet and onto the slices. Transfer to a plate and let cool, about 10 minutes.