[M:B]

Say I have a saturated solution of sodium sulphate and I add a few drops of concentrated sulphuric acid. What will the result be? Will a precipitate of Na2SO4 form due to the dehydrating ability of H2SO4? Or can sulphuric acid only remove H2O from compounds that have inherent H2O?

[enahs]

http://en.wikipedia.org/wiki/Sodium_sulfate#Physical_and_chemical_properties

[AWK]

Enahs link is rather useless in this case. Think about common ion effect. In this case some Na2SO4 will precipitate

[M:B]

So by adding H₂SO₄ [SO₄^2-] increases resulting in the equilibrium shifting to favour the formation of Na₂SO₄?

[AWK]

So by adding H₂SO₄ [SO₄^2-] increases resulting in the equilibrium shifting to favour the formation of Na₂SO₄?

This is (probably) the main process (formation of solid hydrated Na2SO4 - hydration depends on temperature of the solution). The next process will be:
SO₄^2- + H₂SO₄ = 2HSO₄^-.
This process may be important for larger amounts of sulfuric acid