Answer: make it unexpected; make it human. Vivienne Parry:

Every great science story has an “I never knew that” moment at its heart: some utterly delicious factoid or piece of information so counterintuitive it hauls you up short and forces you to read it a second time. […]

Those who are not into science think it is an emotion-free zone populated by dry-as-dust facts, but look carefully at a great science story and you’ll find plenty of emotion, usually pressed between quotation marks. Scientists believe that journalists talk to them because we want to quote them on the science, but actually what we really want to quote is how they felt.

Emphasis mine.