I cannot explain this topic fully, but I can give you some ideas as to where to look. This is a really good experiment.
If you take a look inyour basic undergraduate organic textbook, you can find the explanation for this solubility.
The text I am using is Streitweiser, Heathcock and Kosower Introduction to Organic Chemistry, 4th edition.
In this text, in the basic section of nuclophilic reactions, they talk about solvent properties. on Page 184, there is a simple explanation of what happens when you dissolve a salt in a solvent. The Dielectric Constant is a measure of the reduction of the Electric Field in the medium, and materials that are polar, will align with charges in solution, and with thermal motion, will move closer to the ions. The dielectric constant of the medium will tell you the polarity of the solvent, and will indicate how well it will solubilize salts, and ions in solution.
Hexanes should not solubilize hardly any salts at all. The fact that it does means that the bonds are fairly weak in the salt, it would have to be stabilized by thermal velocity to prevent crystallization. Take a look at the bond strengths of the salts, and remember to include resonance stabilization, and compare the solubilities of the salts in various dielectric constant solutions.
Hopefully this should give a good direction to take a look at.