Sugar (sucrose) can easily increase density.
1 kg sucrose + 1 l water gives 1,65 l solution (density 1,21 kg / l).
1,5 kg sucrose + 1 l water gives 2 l solution (density 1,25 kg / l).
2 kg sucrose + 1 l water gives 2,3 l solution (density 1,30 kg / l).
But it is a short time effect, as within 2- 3 days solution will go bad, unless somehow conserved.