For homemade microwave caramel popcorn, first place the popcorn corn in a microwave-safe container and pop at 1000 watts for two and a half minutes. Then lay out the popcorn on a parchment paper in about three layers.
Stir the powdered sugar and water in a suitable glass bowl until a thick paste forms. Heat this in a microwave oven at 700 watts until it turns an orange-brown color. This will take about 3-4 minutes. Empty the hot liquid (be careful not to reach in!) over the popcorn, stir a little with a spoon.
After about 2 minutes, remove the homemade caramel popcorn from the parchment paper in the microwave and let it cool completely on a flat plate.
Homemade caramel popcorn from the microwave can be refined with a little fleur de sel. Simply add on top while the caramel is not yet completely dry.