Emmy Noether was initially interested in invariant theory. But how did she become interested in abstract algebra? And why did she become particularly interested in ring and ideal theory?
Ernst Fischer was hired by Erlangen in 1911. He is known to us today for his work in analysis (Riesz-Fischer theorem), but he worked on algebraic topics at Erlangen (and his thesis was on determinants). He influenced Noether's direction of work towards Hilbert's approach to studying polynomial rings, which had success in proving results of sweeping generality without tedious computations; think of Hilbert's basis theorem. Noether's thesis had hundreds of calculations in it and she never thought highly of this work. That experience perhaps made her more interested in a style of math that was more conceptual and less computational, which in her case turned out to be abstract algebra.