Once the vapor pressure of a liquid equals atmospheric pressure that liquid boils and temperature remains constant. By increasing atmospheric pressure a higher boiling temperature results. Some solids, such as carbon dioxide, do not pass through a liquid phase and sublimate to the gaseous phase.
Aha! I do remember the triple-point! :) And thank you for not smacking me for being a dolt.
And, I love the use of the word slag: I grew up in an area well populated by slag dumps from the local steel mills.