I don't remember doing this proof
Mao, but I do remember using a really cumbersome method to prove some acidity constant question. (Then finding an elegant method

)
But yes, using the theory of equilibrium, we can prove this with mathematics
(which you don't need to do or know for VCE Chemistry!):
Take a reaction:

with

Suppose that the initial concentrations (at equilibrium) are:

,

, and

, where

.

Now, half the volume so that every concentration is doubled. Now,

The system is now thrown into dis-equilibrum, and

must decrease in order to return to

.
Thus,

and

must decrease and

must increase (via the backward reaction of the chemical equation above).
Following the reaction, the system will re-establish the equilibrium as follows:

,

,

,
where

(2c-x)}{2a+x})
Since

:
(2c-x)}{2a+x} = \frac{bc}{a})
(***)
 \left(\frac{c}{a}\right))
Since

:
 \left(\frac{c}{a}\right) > \left(\frac{2a}{2c}\right) \left(\frac{c}{a}\right) = 1)



Similar working from line
(***) can be done to conclude

as well.
This proves that the final equilibrium

and

is greater than the initial equilibrium

and

, despite the principles of equilibrium working to reduce both

and

from

and

respectively.