An Unfinished potion is the result of using an identified herb on a Vial of Water. Making unfinished potions, or using unfinished potions to make complete potions, is a key part of the Herblaw skill.
The unfinished Jangerberries potion is a player made-mistake when trying to make the ogre potion, as the correct mixture is Guam leaf followed by Jangerberries. When examined this potion reads "I need another ingredient to finish this potion"
The Guam leaf + Jangerberries potion yields an unfinished Shaman potion, which when completed with ground bat bones becomes Ogre potion
The examine text for an unfinished dwarf weed potion is I need another ingredient to finish this Dwarfweed[sic] potion