Figure below shows the change of the temperature when a gas is cooled to become solid.
Q & A
Q: Why the temperature remained unchanged from Q-R and S-T?
A:
The temperature remains unchanged because the heat released during the formation of the intermolecular forces compensates the heat losses to the surrounding.
Q & A
Q: Why the temperature remained unchanged from U-V?
A:
Because the temperature of the solid has reached the temperature of the surrounding.