Why can water dissolve so many substances?
Since this is not my area of expertise, I searched Google under the key words "water dissolve substances" to get these possible sources:
http://www.visionlearning.com/library/module_viewer.php?mid=57
http://www.shambles.net/pages/learning/ScienceP/Dissolve/
http://www.concord.org/~btinker/xworkbench_web/unitIII_mini/act_sol_solutions.html
http://www.lenntech.com/water-chemistry-FAQ.htm
http://ga.water.usgs.gov/edu/waterproperties.html
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search.
I hope this helps. Thanks for asking.