The law for universal gravitation is
F=G(m1m2/d^2)
The diatomic molecule H2 has an extremely low boiling point because only weak Vander waals forces are present between the atoms of hydrogen molecule. This weak inter-molecular forces are easily broken when heat is apply resulting in low boiling point.
Basically the sugar breaks down until it’s eventually evaporated and spreads to different parts of the water solution and while it’s spreading the chemicals and the flavors in the sugar are going into the molecules and atoms in the water and mixing to make the water solution taste sweet just like sugar. So i would say it would be a physical change not a chemical change.