1. as intensifier.
In informal conversation ever is sometimes used as an intensifier immediately after an interrogative word such as who, what, why, etc.: Who ever can that be? / What ever did you say to him? / Why ever should you think that? These uses should be distinguished from the one-word forms whoever, whatever, etc., which are relative pronouns: I'll do whatever you want. See whatever, what ever; whoever, who ever.
2. did you ever?
This expression is informal only, and has a distinct Victorian ring:

• ‘And where is she now?’ ‘In a studio.’…‘Did you ever!’ said Mrs. Fanshaw —Peel City Guardian, 1892.

3. ever so.
An older use after if or though with the meaning ‘at all, in any degree’ now sounds archaic and has almost disappeared:

• Though Sir Peter's ill humour may vex me ever so, it never shall provoke me —Sheridan, 1777.

It is now overshadowed by the same phrase used (since the mid-19c) in positive contexts as an intensive meaning ‘extremely, immensely’:

• It's the greatest idea, and I'm ever so grateful —J. Leland, 1987

• Broken bones sounded ever so unpleasant —O. Drake, 2001.

This use is largely restricted to conversational English.

Modern English usage. 2014.