That last bite is the best - because it is the last!!

Saving the Last for Best: A Positivity Bias for End Experiences

Ed O’Brien and Phoebe C. Ellsworth

Psychological Science 23(2) 163–165 (2012)

DOI: 10.1177/0956797611427408

The researchers used 5 different flavoured chocolates to see if the test subjects found a difference in the taste of the last one.  The hypothesis was that knowing that something is ending makes it all that much more important to you.  The subjects were given the chocolates randomly and asked to rate the flavours.  When given the fifth one, the subjects were either told that it was the "next one" or the "last one".  When told it was the "last one" about 64% of the subjects rated the last one their favourite.