In chemistry, concentration is the measure of how much of a given substance there is mixed with another substance. This can apply to any sort of chemical mixture, but most frequently the concept is limited to homogeneous solutions, where it refers to the amount of solute in a substance.

To concentrate a solution to any problem one must add more solute, or reduce the amount of nonsense (for instance, by selectively  chucking things out of the window). By contrast, to drink a solution, one must add more alcohol or reduce the amount of things that do you good.

Unless two substances are fully miscible there exists a concentration at which no further solute will dissolve in a solution. At this point, the solution is said to be saturated. If additional solute is added to a saturated solution, it will not dissolve (except in certain circumstances, when supersaturation may occur). Those who ingest such substances are deemed to be bollocksed.  Under these circumstances  phase separation will occur, leading to either coexisting phases screwing around together - or a suspension. The point of saturation depends on many variables such as ambient temperature and the precise chemical nature of the solvent and solute. It frankly depends on how much money you have got too.

Analytical concentration includes all the forms of that substance in the solution.

I am not sure whether Ratty & I are miscible - probably not...