Position racks in the upper and lower thirds of the oven and preheat to 375 degrees . In a small saucepan, bring 2/3 cup sugar, 3 tablespoons cold water, 1 tablespoon corn syrup and 1/4 teaspoon salt to a boil over medium-high heat, stirring to dissolve the sugar. In a medium bowl, combine the syrup with one 14-ounce bag sweetened shredded coconut and let cool. In a separate bowl, whisk together 2 egg whites and 1 teaspoon pure vanilla extract until foamy and thick; stir into the coconut mixture. Drop tablespoonfuls of the mixture 2 inches apart onto each of 2 parchment-lined baking sheets. Bake until golden, switching the pans halfway through, about 15 minutes; let cool completely on racks.