Assuming that with "AR" you are referring to aqua regia or a chloride salt solution of metals.
If you dry or evaporate the water from a solution of metal chloride ions you will have the salts or crystals of those metals as chloride salts. During the process, water is vaporized off, acids concentrate and begin to azeotrope and then decompose into vapors of the acids involved, the acidic salts will dry but will still hold moisture and can still be acidic in nature...
The gold chloride will still be salt of gold and of the acid (chloride ion), as the solution of dissolved gold concentrates as the solution is evaporated, you can come to a point the solution cannot hold the chloride salt of those metal ions, to the point where crystals of those metals begin to precipitate from the solution.
Boiling a solution you can have losses of gold through carryover of gold salts with the vapors and splashing of liquids and gases the process.
Keeping the solution from boiling C.M.Hoke suggested using a steam bath that would provide enough heat to slowly evaporate the solution (over a large surface area) but keep the temperature low enough so as not to actually boil the solution which would be a problem for losing gold in the process...
Gold chloride salt can begin to decompose around 160 deg C.
The gold chloride can become volatile if heated at higher temperatures (>180 deg C.), or baked dry in the process causing loss of gold in the fumes due to chlorine gas evolution carrying gold in those fumes...
When evaporated to salts of metal chlorides (if done properly) even then you may have some salts that will still be water-soluble, some of the gold salts may dissolve In water or some may need HCl added to get the metal back into the solution if the salts are calcined or baked dry some gold may have become reduced to metal in the evaporation process and may not be easy to get it to dissolve without using an oxidizer (Hoke page 55 discusses using chlorates with gold salts baked-on the dish...).
