To clarify some of the structures found in the test tubes, I must define the colored clumps you will come across.  The solid clumps represent the solid composition of the component, corresponding to the particular color.  The transparent clumps with individual molecules inside of them represent the solid solution of the components, which are not quite a solid, but rather a homogenous cluster of component molecules.  The arrows pointing upward denote molecules leaving as vapor as the liquid boils.  And finally, the individual stars, circles, and diamonds represent the individual molecules of each of the components.
 
        Two other features of the phase diagram I would also like to point out are azeotropes and eutectics.  The azeotrope is a minimum or maximum point on a boiling-point diagram at which the liquid and vapor compositions are identical.  Minimums in the boiling point are due to strong positive deviations from Raoult’s law.  Conversely, maximums are due to strong negative deviations.  The eutectic, found in melting-point diagrams, is the minimum melting point and is found at the intersection of the curved lines representing the freezing-point depressions of each component when the other is added to it.