This video teaches you
To thicken syrup without any additives, simply reduce it on the stove. Pour the syrup into a saucepan, then turn the burner on low. Bring the sauce to a low simmer and let it sit for about 10 minutes, stirring occasionally so it doesn’t burn. Leave the lid off so that some of the liquid can evaporate, which is what will cause the syrup to thicken. Test the syrup with a candy thermometer after about 10 minutes. Once it gets to around 223 degrees Fahrenheit, the syrup should be thick enough. Let it cool down for 2 minutes before drizzling it over pancakes or waffles.