Test E has a very low melting point. Its liquid, even at room temperature (approx 70 degrees F). So, the only way to crystalize Test E would be to bring it to a temperature that is in its freezing point range.
Any substance can go back and forth between gas, liquid, solid (if it has those states) a pretty much infinite amount of times. Just depends on a combination of temperature and pressure as different temp and press combinations will lead to a different state.
e.g. (theoretical, not real numbers) If you have a normally liquid Test E (room temp, standard atmospheric pressure of 1atm), and you increased the pressure to say, at some greater pressure it will be a solid again. And, likewise, if you decrease temperature, at some temperature (std pressure) it will become solid again. Or, you can decrease both temp and pressure, etc, etc...you get the idea.
Different substances have different freezing, boiling, melting, and gaseous states in regards to required temp and pressure. e.g. steel has a very high melting point and therefore will remain in its solid (frozen) state until the temperature is increased to a point where it will melt.
Now, just to clarify, not all substances have all three states, and not all substances are equally effected by temperature and pressure. E.G. Think of a space vehicle....0 pressure (close to it) in space, yet its still solid. However, if you took that same vehicle too close to a neighboring star, many of the heat resistant metals would eventually melt given a high enough temp.
