[mana]

hi all
as you know, Li₂SO₄ is a good water soluble salt and it's dissolution is endothermic.
 I have tried some Li₂SO₄ in water, it was dissolved in room temperature easily, but when I heated the solution I expected to see it's solubility decreases and see the Li₂SO₄ solid in my test tube but it didn't happen I heated the test tube until the water bath was boiling and the amount of water in my test tube decreased as well.
by the way, my question is why the solubility didn't decrease by heating?
thanks in advance for your help

[mana]

here is the Li₂SO₄ solubility diagram :

[Hunter2]

How you can see in the diagram ( yellow curve) the soloubility is more or less the same over the whole temperature range. A slightly decrease can be seen.
To see an effect you have to dissolve to the soloubility limit about 342 g/l at 25 °C

[Aldebaran]

Do you have details of the measurements you recorded? For example volume of solvent, mass of solute, temperatures. Also how did you determine whether or not you had a saturated solution at any stage in your experiment?

[Aldebaran]

Whilst considering these questions you might also like to read about nucleation. Wikipedia has a quite accessible description of this phenomenon.