There are some interesting examples given:

Polywater was a form of water which appeared to have a much higher boiling point and much lower freezing point than normal water. […]

Eventually it was determined that many of the properties of polywater could be explained by biological contamination.

When more rigorous cleaning of glassware and experimental controls were introduced, polywater could no longer be produced.

It took several years for the concept of polywater to die in spite of the later negative results.