When looking at a graph of comparing temperature and specific volume, we see that for increasing pressures, the boiling point increases and that the length of the saturated liquid-vapor line decreases.
So, there's really two questions here, but the following first question will help with answering my main question.
I understand this as because of an increase in pressure, molecules are harder to push apart (as essentially pressure is an external force keeping the molecules together). Is this correct?
However, the main question is why does the saturated liquid-vapor line decrease in length as pressure increases?
The way I understand it is that because we needed a higher boiling point at high pressures, we've already inputted a lot of energy to get to this point, and so the specific volume of the liquid is already quite high for higher pressures, as inputting energy essentially tries to push apart these molecules. Hence, to reach the saturated vapor point, we don't need as much energy to keep forcing particles apart (so the increase in specific volume is not as much).
Refer to graph 2-13 on http://engr.bd.psu.edu/davej/classes/thermo/chapter2.html