High symmetry molecules fit into crystal lattices especially well (higher mp), but are volatile for having fewer van der Waals interactions (lower bp)

Pentane mp −130 °C, bp 36.1 °C  
isopentane,  mp −160 °C, bp 27.2 °C  
neopentane, mp −18 °C, bp 9.5 °C

octane, mp −57 °C, bp 125 °C  
2-methylheptane, mp −110 °C, bp 117 °C  
2,2,4-trimethylpentane, mp −107 °C, bp 99 °C  
2,2,3,3-tetramethylbutane, mp 101 °C, bp 107 °C  
cubane, mp 131 °C, bp 133 °C (sublimes at room temp)

decane,  mp −30 °C, bp 174 °C  
isodecane, mp −75 °C, bp 167 °C  
adamantane mp  270 °C, sublimes