반복 중에 Python 목록에서 요소를 제거하면 예기치 않은 결과가 생성되는 이유는 무엇입니까?

a = list(range(10))
remove = False
for b in a:
    if remove:
        a.remove(b)
    remove = not remove
print(a)

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]       <-  b = 0; remove? no
 ^
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]       <-  b = 1; remove? yes
    ^
[0, 2, 3, 4, 5, 6, 7, 8, 9]          <-  b = 3; remove? no
       ^
[0, 2, 3, 4, 5, 6, 7, 8, 9]          <-  b = 4; remove? yes
          ^
[0, 2, 3, 5, 6, 7, 8, 9]             <-  b = 6; remove? no
             ^
[0, 2, 3, 5, 6, 7, 8, 9]             <-  b = 7; remove? yes
                ^
[0, 2, 3, 5, 6, 8, 9]                <-  b = 9; remove? no
                   ^