In a medium saucepan over medium-high heat, combine the sugar and water, and bring to a boil. Cook, without stirring, using a wet pastry brush to push down any crystalized sugar pieces around the inside of the saucepan. Continue boiling until deep amber in color, 5 to 7 minutes. Remove from the heat and slowly whisk in the cream.
Return the pan to medium-high heat, then stir in the maple syrup and bourbon. Cook at a low boil for 1 minute, until a thick, smooth sauce forms. Remove from the heat and add the butter and vanilla, whisking until smooth. Season with salt and serve warm or at room temperature. Make ahead: The sauce can be made up to 1 week ahead. Cover and chill until ready to use.