Phase transition for an ideal fluid
Ideal gas and ideal fluid are not the same. Ideal fluid has molecular interaction that is even throughout different entities, and has no viscocity, and no compression. 

Yes, ideal fluid is modeled so that it will go through phase change, but you would have to consider the gas from ideal fluid as a pseudo- real gas, since it has molecular interaction.

An ideal gas has no volume, has no interaction, will not go through any sort of phase change. 

Hope this helps.