The density of the liquid and solid states of a substance are often similar. explain?

In most of the cases, density is closely related to the amount of force between the atoms/molecules of a substance and because this force is almost a constant, the density of its liquid or solid state will be similar. The only difference would be an increase in the temperature when the substance is in it's liquid state, but even in this case, since the basic molecular or atomic or ironic forces are the same, perhaps a little lesser, the density would be comparable.