Consider a strong acid $\ce{HA}$. In a $\pu{1000 mL}$ of hexane (assume it is unable to accept a proton) we "dissolve" (this can mean forming a suspension with vigorous stirring - otherwise we can use a polar solvent which cannot accept a proton) $\pu{1e-30 mol}$ of the acid along with enough water to remove all the protons.
Now we have extremely dilute solution of $\ce{H+}$ where autoprotolysis is insignificant compared to the volume of solvent, so according to $\mathrm{pH} = -\log[\ce{H+}]$, pH should be extremely high. However, we are still using an acid, so pH should not be too high. What accounts for the difference?