Evaporating the excess water content by cooking it longer is truly the only way ... next-best trick you can use: Tomato paste. Adding the thick tomato paste will naturally thicken up the sauce ...

His advice is simple: "Adding sugar and letting it reduce slowly is the best way to thicken it when being used as a glaze." Using a BBQ sauce as a base is an easy hack for a classic grill flavor ...

The benefit of cooking the flour in the butter is that you'll avoid the unpleasant taste of raw flour and you'll also be able to thicken stews, gravies, or sauces ... for other ways to thicken ...