A mixture is a combination of two or more substances in any proportion. The substances do not combine chemically; they intermingle and keep their own properties. A homogeneous mixture has the same composition throughout, and a heterogeneous mixture varies. A solution is a homogeneous mixture of a solute dissolved in a solvent, with particles too small to see, settle or filter out. Water dissolves more substances than any other liquid, and a solution becomes saturated when no more solute will dissolve. Because the parts keep their properties, mixtures can be separated by filtering, settling or evaporating.