In a springform pan, fit the piecrust in the pan, pressing excess crust up the sides of the pan. Chill for 30 minutes.
Preheat oven to 400 degrees and heat the springform pan with crust in oven while you make the filling (no more than 10 minutes). Make caramel by placing the sugar and water in a small nonreactive pan over medium high heat, stirring constantly. When the sugar mixture turns amber, immediately remove the pan from the heat so the sugar does not burn. If you can, place the pan in a bowl of cold water to stop the cooking process.
Remove springform pan from oven, pour the caramel mixture into hot crust filled pan, and then fill with mango slices. Be careful, the pan is hot! Bake for about 25 minutes or until the pastry is lightly browned.