How concentrated can an acid be?
I am talking about dissolving in water since an acid needs some sort of solvent to dissociate.


No, it doesn't. You neglect autoprotolysis where the water-free acid itself is the solvent.

\begin{align}
\ce{2H2SO4 &amp;&lt;=&gt; H3SO4+ + HSO4-}\\
\ce{3HF &amp;&lt;=&gt; H2F+ + HF2-}
\end{align}