Depends on the type of glass. As you warm the water, you also warm the glass. If the glass has a high coefficient of thermal expansion like ordinary common glass (8.5 ppm/degC) then the container will get bigger more quickly than if the glass is a low coefficient glass like Pyrex (3.2 ppm/degC).Laboratory glassware is often made from Pyrex, so if you do this in a Pyrex beaker, the container will grow by a factor of 1.000256 in each linear dimension, and its volume will increase by about the cube of this (1.000768), adding about 0.768 ml to the volume of the nominally 1 liter beaker. Meanwhile, the water will expand by a factor of 1.01656, adding 16.56 ml to the volume of the water. The difference is about 15.8 ml. I expect the overflow to be about 16 ml.Doing this measurement will be complicated by the meniscus effect. You could also do it by watching the water level rise in a 1 liter graduated cylinder made from Pyrex.I took my expansion numbers from Thermal expansion - Wikipedia