Preheat the oven to 350 F. Spray the inside of a 10 cup bundt pan with an oil-flour combo, such as Baker's Joy. Set aside.
Place the sugar and water into a small saucepan over medium heat. Whisk it as it melts; when it is completely melted and mostly clear (the brown sugar will keep it from becoming completely clear), add the salt, vanilla and liquor. Let simmer for 1 minute. Brush onto the cake while still warm.